Melt-blown non-woven process: polymer feeding - melt extrusion - fiber formation - cooling - into a network - reinforcement into cloth.
Development of melt-Jet nonwovens technology -- Two-component melt-jet technology
Since the 21st century, the development of melt - jet nonwovens technology in the world has advanced by leaps and bounds.
Sheath-core:
Can make nonwovens feel soft, can be made into concentric, eccentric, special-shaped products.Generally, the core is made of cheap material, and the expensive polymer with special or required properties is the outer layer, such as polypropylene core and nylon outer layer to make the fiber hygroscopic.The core is polypropylene, and the outer skin is adhesiveable low melting point polyethylene or modified polypropylene, modified polyester, etc.For carbon black conductive fiber, the conductive core is wrapped in it.
Joint type:
Nonwovens with good elasticity are usually made of two different polymers or the same polymer with different viscosities into parallel two-component fibers. The different thermal shrinkage of different polymers can be used to make spirally crimped fibers.For example, 3M company developed melt-sprayed PET/PP two-component fiber nonwovens. Due to different shrinkage, the nonwovens form spiral crimp, which makes nonwovens have excellent elasticity.
Terminal type:
this is in the three-leaf type, cross type and terminal compound another kind of polymer, such as do antistatic, moisture conductivity, conductive fiber can be on the top of the composite conductive polymer, not only can be conductive, conductive, antistatic, and save the amount of conductive polymer.
Microdenier type:
Orange petal shape, strip strip type component can be used, also can be sea island type component.Using two incompatible polymers to peel off to make a superfine fiber network, or even a nanofiber network, such as kimberly-Clark's strip-type two-component fiber, is a super-fine fiber network that takes advantage of the fact that the two-component fiber made from two incompatible polymers can be completely peeled off in less than a second in hot water.The sea-island type will dissolve the sea to get a fine network of island fibers.
Hybrid:
It is a web of fibers with different materials, different colors, different fibers, different cross section shapes, and even with the leather core mixed with both co-spinning and two-component fibers, so that the fibers have all kinds of properties needed.This kind of melt-jet two-component fiber nonwovens or mixed fiber nonwovens can further improve the filtering property of the filter medium compared with the general melt-jet fiber products, and make the filter medium have antistatic property, electrical conductivity, hygroscopic property, enhanced barrier property, etc.Or make the fiber mesh bond, fluffy, air permeability improve.
The two-component molten shotcrete fiber can supplement the deficiency of single polymer performance, such as polypropylene is relatively cheap, but for medical materials, it is not resistant to radiation exposure, so it can be polypropylene as the core, in its outer layer to choose the appropriate radiation resistant polymer wrapped outside can solve the problem of radiation resistance.Thus, the product can be inexpensive and meet functional requirements, such as heat and humidity exchangers for the respiratory system in the medical field, which can provide suitable natural heat and humidity.It has light weight, disposable or easy to disinfect, cheap, but also can play the additional role of removing pollutants filter.It can be composed of two evenly mixed two-component melt-spray fiber network.
The leather core type two-component fiber is adopted, the core is polypropylene and the cortex is nylon.Two-component fibers can also be shaped with a special section, such as three-leaf shape or multi-leaf shape, so that their surface area can be larger. Meanwhile, polymers that can improve filtration performance can also be used in the surface layer or tip part of the fibers.The alkene or polyester fusible spray two-component fiber mesh can be made into columnar liquid and gas filters.Melting spray two-component fiber net can also be used for cigarette filter tip;The core suction effect is used to make high-grade ink suction core.The core suction rod for fluid retention and infusion, etc.
Development of melt blown nonwovens technology -- Melt blown nanofibers
To fabricate nanofibers, the spinneret holes are much smaller than those found in conventional melt injection equipment. NTI can be as small as 0.0635 mm (i.e. 63.5 microns) or as small as 0.0025 ft. Modular spinneret panels can be combined to a total width of more than 3 m.The diameter of the molten spray fiber spun thus is about 500 nanometers.The finest single fibers can be up to 200 nanometers in diameter.
Since the melting and spraying equipment for spinning nanofibers has small orifical holes, if no measures are taken, the output is bound to be greatly reduced. Therefore, NTI adopts the method of increasing the number of orifical holes, and each spinneret plate has 3 or more rows of orifical holes.By combining a number of unit components (depending on the width), the yield during spinning can be greatly increased.The actual situation is that when 63.5 micron holes are used, the number of holes in a single row of spinnerets per meter is 2880. If three rows are used, the number of holes in a single row of spinnerets per meter can reach 8640, so that the output can be comparable to that of spinning ordinary molten shotcrete fiber.
Because thin spinnerets with high density holes are expensive and prone to cracking (cracking under high pressure), companies have developed new bonding techniques to enhance the fastness of the spinnerets and prevent leakage under high pressure.
Nanometer fused - sprayed fiber can be used as filter medium, which can improve filtration efficiency significantly.There are also data showing that because the fiber in nanometer melt-jet nonwovens is thinner, the melt-jet fabric can be combined with spunbonded fabric with a lighter gram weight, which can still withstand the same water head pressure, and SMS products made from it can reduce the proportion of melt-jet fiber.
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Post time: Jul-28-2020